The present invention relates to a battery charging device for charging batteries, and particularly to a battery charging device that performs charge while forcibly air-cooling batteries such as nickel-metal hydride batteries that generate a large amount of heat at the time of charging.
Nickel-metal hydride batteries are being presently used as batteries employed as power sources for use in power tools or the like. While such nickel-metal hydride batteries enable an increase in capacity than compared to nickel-cadmium batteries, they exhibit drawbacks in that the amount of generated heat at the time of charge is large, and in case a high temperature is reached through the heat generation, electrodes of internal cells of batteries or separators are degraded to thereby shorten the life of the batteries. In view of this fact, it has been proposed for an invention as, for instance, recited in Japanese Utility Model Application Unexamined Publication No. 6-54209 (1994), wherein an air-blower is provided in a battery charger for supplying air to terminal portions while an airflow path passing through batteries are formed in a battery package, and air from the air-blower is communicated through the batteries with the air-blower being attached to the battery charger for restricting rises in temperature of the batteries.
With this arrangement, it is enabled to restrict rises in temperature of nickel-metal hydride batteries. Particularly when air is continuously supplied also upon completion of charge, the nickel-metal hydride batteries, which have reached a high temperature at the time of completion of charge, may be cooled in a short time. However, in case of an abnormal condition of the air-blower, the nickel-metal hydride batteries reach a high temperature since charge is performed in a short time with a large amount of current presupposing that cooling is performed through forced air-cooling, and the batteries will be exposed to the high temperature condition for a long time after completion of charge so that shortening of their lives are unavoidable. Particularly, due to the provision of the airflow path in the battery package, impurities are apt to enter the airflow path when the battery package is being used by being attached to a power tool, and it may happen that appropriate cooling cannot be performed owing to clogging of the airflow path. While such conditions are fatal that cause shortening of life of the batteries, such clogging of the airflow path in the interior of the battery package may be hardly found on visual inspection.
The invention has been made to solve the above-described subjects, and it is an object thereof to provide a battery charging device with which abnormalities of a cooling means can be appropriately indicated.
A still further object of this present invention is to provide a battery charging device in which clogging of the airflow path provided in batteries can be detected.
In order to accomplish the above objects, a battery charging device provided with a cooling means for continuing cooling of batteries also upon completion of charge, according to the present invention, is characterized by comprising:
a judging portion for judging whether a battery temperature at the time of completion of charge is higher than a presumed temperature for cooling the batteries by not less than a specified value, and
an abnormality indicating portion for indicating an abnormal condition in case it is judged by the judging portion that the temperature is higher by the specified value.
In the invention, an abnormal condition is indicated in case it is detected that a temperature of batteries at the time of completion of charge is higher than a presumed temperature after cooling of the batteries by not less than a specified value. With this arrangement, in case abnormalities shall occur in the cooling means, such abnormalities can be detected and indicated.
A battery charging device provided with an air-blowing motor for continuing supply of air to batteries provided with an airflow path also upon completion of charge, according to the present invention, is characterized by comprising:
a judging portion for judging whether a battery temperature at the time of completion of charge is higher than a presumed temperature for cooling the batteries by not less than a specified value, and
an abnormality indicating portion for indicating an abnormal condition in case it is judged by the judging portion that the temperature is higher by the specified value and in case the air-blowing motor is continuing its operations.
In the invention, an abnormal condition is indicated in case it is detected that a temperature of batteries at the time of completion of charge is higher than a presumed temperature after cooling of the batteries by not less than a specified value and in case an air-blowing motor is continuing its operation. In other words, by detecting a condition in which the battery temperature does not decrease while the air-blowing motor is being operated, clogging of the airflow path of the batteries may be indicated.
In accordance with the more preferred teaching of the present invention, the abnormality indicating portion further indicates an abnormal condition when the air-blowing motor cannot be rotated.
In the invention, an abnormal condition is indicated in case the air-blowing motor cannot be rotated, so that an abnormal condition of the air-blowing motor can be appropriately indicated.
A battery charging device provided with an air-blowing motor for continuing supply of air to batteries incorporating therein a memory means and being provided with an airflow path also upon completion of charge, according to the present invention, is characterized by comprising:
a charge current controlling portion for judging whether an abnormal condition is stored in the memory means incorporated in the batteries, and for performing charge at ordinary current in case no abnormal condition is stored, and for performing charge by decreasing the charge current in case an abnormal condition is stored,
a judging portion for judging whether a battery temperature at the time of completion of charge is higher than a presumed temperature for cooling the batteries by not less than a specified value, and
a memory portion for storing an abnormal condition to the memory means incorporated in the batteries in case it is judged by the judging portion that the temperature is higher by not less than the specified value.
In the invention, clogging of the airflow path of the batteries is detected by a judging portion in case the battery temperature at the time of completion of charge becomes higher than a presumed temperature after cooling of the batteries by not less than a specified value, and a memory portion stores such abnormality in a memory means incorporated in the batteries. A charge current control portion further judges whether the abnormality that has occurred at the previous charge is stored in the memory means incorporated in the batteries, and in case the abnormality has been stored, the charge current is decreased for performing charge. With this arrangement, batteries that may not be appropriately cooled owing to clogging of the airflow path may also be charged in an optimal manner by decreasing the charge current.